Animal Instinct
by Chirusse
Summary: Warning: SLASH. A challenge by one of my friends: Lupin has a bit of a problem once a month, besides becoming a werewolf, and Snape is more than happy to assist.


** Author's Note: This story contains slash. That means boy on boy action, if you don't know that. Read at your own risk. Besides that, I'd like to tell Marisa to please enjoy this fiction, as it was written for her, and thank her for our wonderful Potter-related discussions. This fiction really helped me get rid of my writer's block, which had become a REALLY big problem. Please enjoy!**

Harry was sitting across from Lupin, glaring hatefully at Snape, who had set a steaming goblet of Wolfsbane Potion in front of Lupin. Snape ignored Harry's stare.

"You should drink that directly," he said, emotionless.

"Yes, thank you, Severus," Lupin replied, with a pleasant smile. Snape's eyes flicked at Harry, but he did not voice any of his thoughts. There was an uncomfortable silence between the three, and Harry realized that it might be time for him to leave.

"Professor Lupin," he started, staring down at the goblet and then back at Snape, as if he was accusing him of something with his eyes, "I'll see you Monday morning, then." He exited the room, turning to look back at Lupin and Snape before he shut the door behind him.

As the boy left, the careful façade of Snape's face broke away.

"How is the pain?" He asked Lupin, who was gulping down the Wolfsbane, trying not to breathe in the terrible odor of the potion.

"I will be alright, Severus. I've been transforming since I was very young, as you know. I'm used to it by now."

Snape's face grew a bit more guarded.

"Does Potter know?"

"I haven't told Harry anything yet, Severus. He won't do anything, even if he finds out something."

"You don't know Potter," Snape said. "He will tell his friends, and then we can only imagine where that information will end up."

"Harry is a good boy. You haven't even tried to get to know him."

"I know perfectly well what he is like; arrogant and big-headed, just like his father!"

"He is also compassionate and chivalrous; Harry does what is right. You are severely misjudging him. Sometimes people and their motives are not what they seem, Severus." Lupin was eyeing Snape in a careful way, as if to make a point.

"We are no longer speaking only of Potter. Are you referring to that mangy, mutt-of-a-friend you had? Black?" Snape was sneering. Lupin did not answer.

Snape turned away from him.

"I do not wish to speak about the company you kept during our years as students," he ground out.

"Then what do you wish to speak about?" Remus asked, getting up from his desk and walking over to Snape. He traced the line of Snape's shoulder with a finger. Snape raised an eyebrow.

"Has it become unbearable?" Snape teased, touching Lupin's chin. "Are you already aching?" He nudged Lupin's knees apart with this own, and Lupin stepped closer. There was a tent in his pants, and he began rubbing himself against Snape like a mad dog.

Every month, when the full moon approached, Lupin would have an insatiable need for sexual relief. The feeling, studied for years by those in the Ministry, stemmed from his wolf's animal instinct to procreate. Luckily, Snape had quickly become Lupin's object of affection, and was very grateful to help him with this problem.

"That's not going to be enough, Lupin, and you know it," said Snape. Lupin had begun to pant and whine.

"Severus, I believe using my given name would be appropriate now," he gasped, and pawed at Snape's back.

"Very well, _Remus_, shall we take this some place else? What if one of your students was to walk in?" He took his partner's face and gave him a rough, demanding kiss.

"Then lock the door," Remus responded, tightening his grip. His pants were becoming uncomfortable, and Snape's leg was not helping his problem. Snape took out his wand and cast a silent locking spell.

"Happy?" He asked, smoothing down Lupin's hair.

"Not… really," Lupin complained, jutting his crotch onto Snape, trying to gain some leverage.

"I see," Snape whispered, "Why don't you let me help you with that?" He grabbed Lupin's crotch and squeezed.

"Severus, please," Lupin moaned, taking his partner's lips again. He lowered his hands to his fly, unzipped his trousers, and pulled Snape's hands inside.

"You're so very wanton today, Remus. You usually aren't so impatient. Did you not do this for yourself last night?"

"Can't," Lupin panted, thrusting into Snape's hand. "Doesn't help anymore. Can't do it myself."

"Oh, dear," Snape responded, nipping Lupin's ear and neck. "But you're so much more enjoyable when you're this shameless." He dropped to his knees and faced Lupin's crotch.

"Now what should I do here?" He teased. Lupin whimpered and whined.

"You need to tell me what you want, Remus. Say it."

"Please, Severus, _please_!" Lupin pushed his trousers off his hips and pulled his aching need out of his underwear. Snape's hands massaged the terse abdominal muscles of Lupin's lower half, and pulled the underwear down to the floor with the trousers.

"You need to be a bit more explicit, Remus. I might misunderstand."

Lupin was implementing every ounce of self-control he possessed to not thrust himself into Snape's mouth.

"Merlin, Severus, _please_ suck my cock," he nearly screamed.

"Very well, Remus," Snape said, and swallowed him whole.

Lupin was in bliss. Snape's mouth was sucking away the very ache in his cock, turning it into inconceivable pleasure. He knotted his fingers in his partner's hair and turned his head to the ceiling in rapture. He felt Snape's tongue snake along the underside of his shaft to the head. Lupin was turned to jelly as the sucking increased again. After a few minutes, he felt his end coming near.

"Severus, I'm going to…" he trailed off and bucked his hips into Snape's mouth. White semen was dribbling out the corners of usually sneering, sarcastic lips. He stared down at Snape, who was drinking his essence.

"Something the matter, Remus?" Snape smirked, standing again. "Would you like a taste?" He took Lupin's lips and kissed. Lupin felt Snape's own arousal poke at his hip. Snape began to undo the buttons of Lupin's shirt.

"Severus, take off your robes," pleaded Lupin.

"Do it yourself, I'm a bit occupied," Snape said, mid-kiss. Lupin ran his fingers down the buttons of Snape's robes. His wand was in his pocket, and would make the entire affair of undressing a bit easier. He reached to get it, but was stopped.

"What are you doing?" Snape's lips were attached to his neck, and hot breath was tickling him.

"Making this a bit faster. I don't know if I can wait. I just came, but I'm already like this again." Lupin's cock was half awake, standing almost at attention once more, struggling to meet Snape's arousal in answer.

"You will wait, Remus. I assure you, I am quite satisfactory to your needs, am I not? You realize, from our previous encounters, that I will give you release many times a night? Do not rush through the appetizers to get to the main course, as they have been as carefully prepared and taste just as good." He kissed him once more.

Lupin swallowed thickly and undid Snape's buttons, one by one, revealing a pale white chest covered in a few black hairs. He spread his palms over Snape's sternum with one hand, and slipped into Snape's trousers with the other. A rumbling growl sounded from Snape's throat as Lupin wrapped his hand around Snape's cock.

"You're so eager, Remus. How many times must I tell you to _wait_?"

Lupin's hips twitched and he roughly pushed off Snape's outer robes. He sunk down to the ground, pulling off Snape's shoes, socks, and trousers. Snape was fighting his movements to rid Lupin of his shirt completely. They stood before each other, the only barrier being Snape's underwear.

Lupin attacked Snape's lips, kissing him like a desperate man, grinding his body into his partner. They fell to the floor in a tangle of limbs, Lupin on top.

"Severus, please do something," he moaned, his cock fully erect again.

"So shameless," Snape whispered, sitting up and sucking on Lupin's neck. He scooted and maneuvered himself out of his underwear. Lupin took his cock in his hands and rubbed it against his own.

"Yes, good boy," Snape moaned, holding Lupin's head against his shoulder. Lupin was moving himself up and down, sliding their shafts against each other, creating delicious pressure and pleasure. Precum was leaking from the tips, and making their movements slippery.

"I can't hold them both, my hands are too small," Lupin cried, panting. Snape wrapped his hand around Lupin's and squeezed harder. Tears formed in the corners of Lupin's eyes, and he exploded over their chests.

Lupin fell and curled into Snape's chest, his own chest heaving, and his eyes closed. He rested for a moment until he realized what he had forgotten.

"Severus! I'm sorry, I should have…" He sat up stared down at Snape's _still_ erect cock. He licked his lips and lowered his face, but then paused and looked back up.

Snape raised an eyebrow.

"I'm losing my patience, Remus. Do get on with it." Remus grasped the base of Snape's cock and began to suck.

There was another feral growl from Snape, and the thrusted his hips up into Lupin's unsuspecting mouth. Lupin almost choked for a second, but quickly recovered, wanting to get to the main event of their meeting. Snape grasped the back of his head and pushed him farther down.

"You're so good Remus, so damn good," he moaned. "I can't wait to bury myself in you." He began to pant and his chest was rising and falling rapidly. Lupin was licking the precum from his shaft, squeezing the base with his hands, and watching Snape writhe.

Snape began to move his hips into Lupin's mouth rhythmically, in spite of his partner's struggle to keep up with the movements.

"Get ready, Remus," he warned, before spilling himself in Lupin's hot throat.

"Swallow it all," Snape coaxed, as Lupin began to cough. He caressed Lupin's hair and was released with a pop.

The two men sat and stared at each other for a moment. Snape finally spoke up.

"It seems we have come to an impasse, Remus," he said. "For us to enjoy the evening, we will need time for me to become erect again." Snape eyed Lupin and raised an eyebrow.

"It seems your werewolf ancestors were very used to lengthy… activities on nights such as this." Lupin looked down and saw that his cock was still interested in whatever "activities" Snape suggested.

"I'm sorry Severus, I know I'm tiring you out," Remus said. "I tried to take care of some of it myself, but it hasn't done any good."

"So you said earlier," replied Snape. "Yet, I am curious. Would you please demonstrate your technique?" Lupin stared at him in disbelief.

"You want me to wank for you?" He asked, incredulous.

Snape smirked and sat back with his hands on his knees.

"Go on then," he urged. Lupin reluctantly reached between his legs and pulled on his cock. It sprang to life with the attention. His face contorted with the pleasure.

Lupin began squeezing and pulling himself, going at a moderate pace that left him looking tortured. A bead of sweat rolled down his forehead.

"Faster, Remus," Snape urged, watching Lupin pant.

"Severus please," Lupin begged, glancing over at Snape with his lust-clouded eyes. "It's no use. I can't do it myself. I need your help."

"Harder, Remus," Snape ordered. Lupin tightened the grip on himself and gasped, moaning as he did what Snape told.

"Play with the head. That's right, good boy, now speed up. Yes, good." Snape had taken his own cock in hand and begun to pleasure himself.

Lupin was squirming on the floor bucking for some release. Desperate, he groaned and crawled over to Snape.

"Stop, Remus," Snape said, pulling away Lupin's hand. His cock was purple from the accumulation of blood, and leaking semen.

"It seems you are correct. You cannot release on your own. Very curious, don't you think?" Snape, feeling a great deal of pity for Lupin, grasped his cock and stroked; once, twice, and Lupin was coming in great white jets. Lupin lay on the ground, panting, and praising Merlin for orgasms.

"Come here, Remus," Snape whispered. Lupin crawled over to his companion, exhausted. He felt himself being lifted and place into Snape's lap, right over Snape's erection. There was a twinge of excitement in the werewolf's belly.

"Are you ready for me?" Snape asked, kissing him. "Prepare yourself." Lupin reached around, split himself, and positioned Snape directly below him. Snape waited for a moment, and then proceeded. When Lupin felt himself breached, he sucked in some air. He looked down to see Snape's face.

Snape's eyes were closed and his eyebrows were furrowed. Lupin touched his face and smiled.

"Are you alright?" He asked gently.

"I should be asking _you_ that question," Snape whispered. "You're so good, Remus." Lupin pushed his hips down onto Snape, inviting him to do as he wished.

Snape began to thrust up, sending the man on top of him into bliss. Harder and faster, he sent Lupin into the heavens, moaning.

"You want this so much, don't you? You've been waiting all day for this, haven't you? I'm the only one who can't satisfy you, aren't I?"

Snape was answered by a mantra of the word, "yes."

The tension between them grew heavy, until Snape could feel Lupin's end coming.

He stopped moving suddenly, leaving Lupin a wanton, screaming, crying mess.

"Get up Remus, and go to the window," He ordered, standing. Lupin did as he was told, struggling with his lust-poisoned body.

"Now bend over," Snape said, behind Lupin. He opened the window to the grounds, where students could be heard laughing and talking below.

"Severus, they'll see!" Lupin protested, but was silenced by Snape's cock in his arse.

"Then you had better keep quiet, yes? Or someone will notice us here." Snape was laughing, and Remus could imagine the smirk on his face. Snape began to thrust again, pushing into Lupin so that he was almost falling out the window. Lupin pushed back into him, his animal instinct taking over.

"Oh, Severus," he moaned, his nails grinding into the sill. An inferno was breaking lose in his abdomen.

Snape growled at him and began to pant, almost abusing Lupin with his cock.

"Remus," he groaned, and his head fell back, his seed coating Lupin's insides. A moment later, Lupin was following him, leaving a mess of semen below the window.

Snape turned him over and stared into Lupin's satisfied stare. A placid smile had found it's way onto both of their faces.

"I will see you next month, then, Remus?"

"Or tomorrow," breathed Lupin.

"Yes, tomorrow," agreed Snape.

**Author's Note: I haven't written slash in forever, actually, so I hope this was okay. There isn't that much slash written for Snape and Lupin (well, not enough for me) so this was really a joy for me to write. **


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